Smoking article with modified smoke delivery

ABSTRACT

A smoking article ( 10 ) comprises a tobacco rod ( 12 ) wrapped with a paper wrapper ( 14 ), and a patch ( 16 ) of material between the tobacco rod and the paper wrapper that extends along the tobacco rod from or near the mouth end (B) to an intermediate point along the rod. The patch has a structure such that it provides a path for smoke from tobacco upstream of the patch to the mouth end that has less resistance to smoke flow than a path through the tobacco under the patch, thus delivering smoke from the upstream part of the tobacco rod to the smoker more efficiently. The patch may also increase the static burn rate of the latter part of the smoking article.

BACKGROUND OF THE INVENTION

The present invention relates to a smoking article with modified smokedelivery.

Smoking articles such as cigarettes comprise a rod of smokable materialsuch as tobacco which is tightly wrapped in a paper wrapper (cigarettepaper). A filter unit comprising one or more filter components may bejoined to the wrapped tobacco rod using a tipping paper. For a uniformcomposition of tobacco rod, the smoke that is delivered through thetobacco rod from the burning tobacco, for any given puffing regime, isdetermined by three main factors: the amount of air drawn in through thecoal during puffing (which depends upon the level of ventilation throughthe cigarette paper); the filtration of the smoke through the remainingunburnt part of the tobacco rod; and the speed of burn of the tobaccorod between puffs (smoulder rate). The smoke delivery from any singlepuff thus depends on the length of tobacco rod remaining, and for astandard puff volume taken from the end of the rod, will result inincreased smoke delivery as the tobacco rod shortens.

The structure of the filter unit and any ventilation included therein(plus any ventilation that may be provided in the tipping paper) willmodify the actual smoke/air combination delivered to the smoker. Hence,the features of the filter unit and the ventilation are typicallyadjusted to provide different brands of smoking article with differentsmoking properties as regards smoke delivery.

However, the structure of the tobacco rod also plays a part in thedelivery of smoke to the smoker, owing to the passage of the smokethrough the unburnt portion of the tobacco. Modification of the tobaccorod structure away from a uniform composition can therefore be used tofurther tailor smoke delivery.

SUMMARY OF THE INVENTION

Accordingly, a first aspect of the present invention is directed to asmoking article comprising: a tobacco rod; a paper wrapper encirclingthe tobacco rod; and a patch of material positioned between the tobaccorod and the paper wrapper and extending longitudinally along the tobaccorod from an intermediate point along the tobacco rod towards a mouth endof the tobacco rod, the material having a structure such that the patchprovides a path for smoke from tobacco upstream of the patch to themouth end that has less resistance to smoke flow than a path through thetobacco under the patch.

This structure modifies the smoke flow compared to an equivalent smokingarticle without a such a patch. Smoke generated from tobacco in thefirst portion of the tobacco rod is provided with a preferential lowresistance path through the smoking article when the smoker draws on thesmoking article, so the smoke is delivered more efficiently. Thisimproves the quality of the smoking experience for the smoker. Anadditional effect is also provided by the patch. The introduction of anopen-structured material into the smoking article increases the staticburn rate of the smoking article over the portion including the patch.The smoker can thus take fewer puffs from the second portion of thesmoking article, thus receiving less smoke and a correspondingly reducedamount of the residues that can accumulate in the tobacco from theconsumption of the first portion of the smoking article.

The length and position of the patch can be selected to provide thedesired proportion of enhanced smoke delivery and reduced smokedelivery. For example, the patch may extend longitudinally from theintermediate point to the mouth end of the tobacco rod. Alternatively,the patch may extend longitudinally from the intermediate point to asecond point between the intermediate point and the mouth end. Thesecond point may be between 1% and 40% of the total length of thetobacco rod from the mouth end. A range of patch lengths are suitable,so that, for example, the patch may extend longitudinally oversubstantially 10% to 90% of the total length of the tobacco rod, or oversubstantially 40% to 80% of the total length of the tobacco rod.

The patch may extend substantially around the whole circumference of thetobacco rod. Alternatively, the patch may comprise one or more portionsof material disposed around the circumference of the tobacco rod. Theseoptions can be chosen as desired to tailor the degree of smoke flowmodification given by the patch.

A variety of combustible materials may be used for the patch. Any suchmaterial that provides the required low impedance smoke flow patch issuitable. The material may be chosen according to its structure with theaim of providing a particular level of smoke flow resistance, forexample. In some embodiments, the patch may comprise a foam material.

In other embodiments, the patch may comprise a corrugated materialhaving corrugations that extend substantially longitudinally along thetobacco rod. Various structures of corrugated material may be employed.For example, the corrugated material may have a laminate structurecomprising a corrugated layer and a non-corrugated layer. Thenon-corrugated layer may be positioned between the tobacco rod and thecorrugated layer, or between the corrugated layer and the paper wrapper.Alternatively, the corrugated material may have a laminate structurecomprising a corrugated layer sandwiched between two non-corrugatedlayers. Also, a corrugated layer may be used alone with nonon-corrugated layers.

In further embodiments, the patch may comprise an embossed materialhaving indentations that extend substantially longitudinally along thetobacco rod, or a grooved material having grooves that extendsubstantially longitudinally along the tobacco rod, or a fibrous sheetmaterial.

The patch may comprise at least one burn-enhancer to increase the staticburn rate of the smoking article over the length comprising the patch.This can be used to tailor the static burn rate and consequently thenumber of puffs that can be taken from the latter part of the smokingarticle.

The patch may have a different colour from the paper wrapper and/or thetobacco rod. This allows detection of the patch by an optical defectdetection system, sometimes used to provide quality control duringsmoking article manufacture.

The tobacco rod may have a reduced weight of tobacco per unit lengthunder the patch compared to upstream of the patch. This both providesspace to accommodate the patch, and further increases the static burnrate of the portion of the smoking article that includes the patch. Anysuitable method can be employed to provide such a tobacco rod. Forexample, the reduced weight may be created by trimming tobacco from theoutside of the tobacco rod, or by trimming tobacco from a tobacco beadfrom which the tobacco rod is to be cut.

The smoking article may further comprise a filter unit attached to themouth end of the tobacco rod. The filter unit may be provided with oneor more ventilation holes.

A second aspect of the present invention is directed to a method offabricating a smoking article comprising: providing a rod of tobacco;disposing a patch of material over the rod of tobacco such that thepatch extends longitudinally along the rod from an intermediate pointalong the rod towards a mouth end of the rod, the material having astructure and the patch being oriented such that, in the completedsmoking article, the patch provides a path for smoke from tobaccoupstream of the patch towards the mouth end that has less resistance tosmoke flow than a path through the tobacco under the patch to anintermediate position along the rod; and wrapping a paper wrapper aroundthe rod.

Disposing the patch of material may comprise positioning the patch onthe rod of tobacco before wrapping the paper wrapper around the rod.Alternatively, disposing the patch of material may comprise adhering thepatch to an inner surface of the paper wrapper before wrapping the paperwrapper around the rod.

The method may comprise: trimming tobacco from the outside of the rod oftobacco over an area where the patch is to be disposed, thereby creatinga reduced weight of tobacco per unit length; and disposing the patchover the rod of tobacco so that the patch covers the area from whichtobacco has been trimmed. Alternatively, the method may comprisetrimming tobacco from the outside of a bead of tobacco over an areawhere the patch is to be disposed, thereby creating the reduced weight;cutting a rod of tobacco from the bead; and disposing the patch over therod of tobacco so that the patch covers the area from which tobacco hasbeen trimmed.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the invention and to show how the same maybe carried into effect reference is now made by way of example to theaccompanying drawings in which:

FIG. 1 shows a longitudinal cross-sectional view through a smokingarticle according to an embodiment of the present invention;

FIG. 2 shows a simplified version of FIG. 1 indicating smoke flowthrough the smoking article;

FIG. 3 shows a transverse cross-sectional view through a smoking articlehaving a patch configured according to one embodiment of the invention;

FIG. 4 shows a transverse cross-sectional view through a smoking articlehaving a patch configured according to a further embodiment of theinvention;

FIG. 5 shows a longitudinal cross-sectional view through part of asmoking article having a patch comprised of foam material;

FIGS. 6A and 6B to 9A and 9B show side views of corrugated patchmaterial and transverse cross-sectional views through smoking articleshaving corrugated patches, for four different corrugated patchmaterials;

FIG. 10 shows a side view of a tobacco rod having a trimmed sectionaccording to an embodiment of the invention; and

FIG. 11 shows a longitudinal cross-sectional view of a smoking articleaccording to an embodiment of the invention comprising a filter unit.

DETAILED DESCRIPTION

The present invention aims to provide a smoking article such as acigarette that delivers smoke to the smoker with improved efficiency fora first portion of the smoking article, and also generates less smokethan a conventional smoking article from all or part of the remainder ofthe smoking article. To address this, a patch of material that allows amore free passage of smoke therethrough than does the tobacco of thesmoking article is positioned under part of the outer wrapping paper ofthe smoking article.

FIG. 1 shows a longitudinal cross-sectional view through a smokingarticle according to an embodiment of the invention. The smoking article10 comprises, in the conventional manner, a cylinder or rod of tobacco12 that is encircled or encased in a paper wrapper 14 (cigarette paper)that forms a tube around the tobacco 14. The smoking article has a firstend A that is intended to be lit, and a second end B that is received inthe mouth of the smoker. Again conventionally, the paper wrapper 14 hasa porosity to air that is low enough for air to preferentially enterthrough the end A of the tobacco rod 12 when the smoker draws on the litsmoking article, rather than through the paper wrapper 14, thus allowingthe smoking article to be smoked.

In accordance with the invention, the smoking article 10 is modifiedfrom the conventional design by the inclusion of a patch 16 of materialarranged between the tobacco rod 12 and the paper wrapper 14. The patchextends from the mouth end B (in this example) in a longitudinaldirection along the tobacco rod to a point intermediate between themouth end B and the end A intended to be lit. The patch is highly porousto the flow of air and smoke in a direction along the length of thesmoking article (and hence will typically be formed from a material witha relatively open structure or be constructed so that the patch itselfprovides as open structure), so that it offers a path for smokegenerated by the lit end of the smoking article and drawn through thesmoking article during smoking that is less resistive to the flow ofsmoke than a path through the tobacco that is overlain by the patch.Hence, smoke produced by burning tobacco from the part of the tobaccorod upstream of the patch has a more free passage to the mouth endthrough the patch material than through the tobacco.

FIG. 2 shows a simplified version of FIG. 1 (in which the shading forthe tobacco and the patch is omitted for clarity) that shows the pathtaken by smoke through the smoking article 10. When a smoker draws onthe lit smoking article, smoke 20 generated by the burning tobaccopropagates through the first part of the tobacco rod towards the mouthend B in the usual manner. On reaching the intermediate point of thesmoking article at which the patch 16 begins, two propagation paths areavailable for the smoke, a first, low resistance, path 22 through thepatch 16 and a second, higher resistance, path 24 through the tobacco12. The path through the patch material is relatively clear and haslittle filtration efficiency compared to the tobacco path. Thedifference in resistance means that the majority of the smoke travels tothe mouth end through the patch 16. Hence, the smoke 20 from theupstream portion of the tobacco rod 12 is delivered to the smoker withless impedance and hence more efficiently than for a conventionaltobacco rod without a patch. The smoker therefore receives the sameamount of smoke for less effort in drawing on the smoking article, or ahigher percentage of the smoke generated during the first puffs on thesmoking article is delivered than normal.

When the burn line of the lit smoking article 10 reaches the patch 16,the open structure of the patch increases the static burn rate orsmoulder rate of the smoking article (this being the rate at whichmaterial of the smoking article burns away in the absence of puffs bythe smoker). This reduces the number of puffs that can be taken from thesecond portion of the smoking article (the portion including the patch),so that the overall amount of smoke delivered to the smoker from thesecond portion is reduced compared to that delivered from a conventionalsmoking article without a patch. This is beneficial in that a largeramount of the residues from the first upstream portion of the smokingarticle that accumulate in the tobacco of the downstream portion isburnt away and a smaller amount delivered to the smoker.

The increased burn rate given by the open structure of the patch 16 canbe further enhanced by providing the material from which the patch isfabricated with one or more burn enhancers. These are substances thatincrease the rate of burning of a material to which they are applied (asa surface layer or by impregnation, for example). The amount and type ofburn enhancer can be chosen in conjunction with the types of patchmaterial, tobacco and paper wrapper to provide a desired burn rateSuitable burn enhancers include citrates, such as sodium or potassiumcitrate. Burn rate additives such as sodium or potassium salts, acetateand tartrate, mono-ammonium phosphate, and di-sodium hydrogen phosphate,sodium and potassium citrate and sodium acetate may also be used, as mayany burn enhancers/additives known to those skilled in the art.

Overall, therefore, a smoking article provided with a patch according tothe invention has increased smoke delivery from a first portion of thetobacco rod and decreased smoke delivery from a second portion of thetobacco rod, compared to an equivalent smoking article without a patch.

FIGS. 1 and 2 show a patch 16 that extends from the mouth end B of thesmoking article substantially to the midpoint of the tobacco rod 12.However, the invention is not so limited, and other lengths of patch maybe used. The length can be chosen to select any desired ratio betweenthe portion of increased smoke delivery and the portion of decreasedsmoke delivery. Lengths between 10% and 90% of the total length of thetobacco rod have been found to be useful, for example lengths in therange 40% to 80%.

Also, the patch need not extend all the way to the mouth end of thesmoking article. A patch that terminates short of the mouth end willstill provide the above-described effects of increased smoke deliveryfrom the portion upstream of the patch and decreased smoke delivery fromthe portion including the patch. The remaining portion downstream of thepatch will provide smoke delivery corresponding to that from aconventional smoking article with no patch. Any spacing between thepatch and mouth end may be chosen, to give the desired overall balancebetween the three types of smoke delivery. For example, the patch mayextend from an intermediate upstream point along the tobacco rod to apoint in the range 1% to 40% of the total length of the tobacco rod fromthe mouth end.

To provide the maximum smoke delivery modification effect for a givenlength of patch, the patch should extend around the full circumferenceof the tobacco rod.

FIG. 3 shows a transverse cross-section through the smoking article 10of FIG. 1, along the line X-X. In the example, the patch 16 completelyencircles the tobacco rod 12. Note that although a gap is shown betweenthe patch 16 and the paper wrapper 14, this is for clarity only; thepaper wrapper 16 will generally be in contact with the patch 16.

Further variation in the amount of smoke delivery modification can beprovided by using a patch 16 that does not extend all the way around thetobacco rod 12. In such an embodiment, the patch 16 comprises one ormore separate portions of patch material. For more than one portion, theportions are spaced apart around the circumference of the tobacco rod12. For even burning of the smoking article, the portions can besymmetrically spaced around the circumference.

FIG. 4 shows a transverse cross-section through a smoking article 10 inwhich the patch 16 comprises three individual portions 26 evenlypositioned around the tobacco rod 12, under the paper wrapper 14.

The patch can be fabricated from any material that has appropriatecombustion and compositional properties for inclusion in a smokingarticle and which provides the required low resistance passage for smokepropagation. Materials which inherently have the desired structure canbe used, such as a fibrous sheet material having a sufficiently openstructure. The fibrous sheet material may be cellulosic sheet materialor tobacco-containing sheet material such as reconstituted tobacco sheetmaterial or tobacco substitute sheet material, for example.Alternatively, materials can be specifically fabricated so as to have asuitable open structure.

For example, a foamed material can be used, wherein the bubbles formedin the foaming process provide an open structure and a substantiallyfree path for smoke. Examples of suitable foamed materials are extrudedtobacco reconstituted materials and foamed band-cast tobacco sheet.

FIG. 5 shows a longitudinal cross-sectional view of part of a smokingarticle 10 in which the patch 16 comprises a foam material.

In other embodiments, the patch may comprise corrugated material, suchas corrugated paper or cardboard. By arranging the corrugations orridges/troughs in the material to run lengthwise along the tobacco rod,a plurality of parallel longitudinal open passages are provided aroundthe circumference of the tobacco rod. A number of configurations ofcorrugated material can be used.

FIG. 6A shows a side view of a first example of corrugated material 30.The material 30 has a laminated structure and comprises a corrugatedlayer 32 sandwiched between an outer flat, non-corrugated layer 34 andan inner flat, non-corrugated layer 36. The extremities of thecorrugations are adhered to the flat layers to form a compositelaminate. The various layers may be made of the same or differentmaterials.

FIG. 6B shows a transverse cross-section through a smoking article 10having a patch 16 fabricated from the corrugated material 30 of FIG. 6A.The outer flat layer 34 is encased by the paper wrapper 14 and thetobacco 12 is in contact with the inner flat layer 36. A first group ofsmoke passages is defined between the inner flat layer 36 and thecorrugated layer 32 and a second group of smoke passages is providedbetween the corrugated layer 32 and the outer flat layer 34.

FIG. 7A shows a side view of a second example of corrugated material 38.In this case, the corrugated material comprises only a corrugated layer32 and an inner flat layer 36.

FIG. 7B shows a transverse cross-section through a smoking article 10using the patch material 38 of FIG. 7A. The absence of an outer layer 34such as that in FIG. 6A brings the corrugated layer 32 into contact withthe paper wrapper 14. The overall structure is equivalent to that ofFIG. 6B, but the second group of smoke passages is defined between thecorrugated layer 32 and the paper wrapper 14 rather than between thecorrugated layer 32 and the flat outer layer 34. This alternativearrangement uses less material but may be found structurally less robustthan the embodiment of FIG. 6B, owing to the open spaces directly underthe paper wrapper 14. Also, the burn rate will be different owing to thereduced amount of material.

FIG. 8A shows a side view of a third example of corrugated material 40,comprising a corrugated layer 32 and an outer flat layer 34. This isequivalent to the corrugated material 38 of FIG. 7A turned upside-down,but the provision of an outer instead of an inner flat layer gives adifferent structure to the resulting smoking article.

FIG. 8B shows a transverse cross-section through a smoking article 10comprising the corrugated patch material 40 of FIG. 8A. The outer flatlayer 34 is in contact with the paper wrapper 14, and a group of smokepassages are defined between the outer flat layer 34 and the corrugatedlayer 32. However, the absence of an inner layer (such as that in FIGS.6B and 7B) means that there is no further group of smoke passagesdefined on the inner side of the corrugated layer 32. Instead, thetroughs on this side of the corrugated layer are filled with tobacco 12.This configuration provides both a reduced increase in the smokedelivered from the upstream part of the tobacco rod compared to theembodiments of FIGS. 6B and 7B, and also a different burn rate. Hence,the structure of the patch material can be chosen to tailor themodification of smoke delivery given by the presence of the patch.

FIG. 9A shows a side view of a fourth example of corrugated material 42,comprising only a corrugated layer 32, with no inner or outer flatlayers.

FIG. 9B shows a transverse cross section through a smoking article 10having a patch formed from the corrugated material of FIG. 9A. The samestructure is achieved as that provided by the corrugated material 40shown in FIG. 8B, with smoke passages on the outside of the corrugatedlayer 32 only (in this case defined by the corrugated layer 32 and thepaper wrapper 14, and tobacco 12 in the troughs on the inner side ofcorrugated layer 32. Less material is used to produce the samestructure, but as in the embodiment of FIG. 7B, the outer robustness ofthe smoking article may be reduced by the absence of an outer flat layerunderlying the paper wrapper 14.

Patch materials fabricated to have a similar structure to corrugatedmaterial may also be used, for example a pair of flat layers having aplurality of parallel ribs extending between the layers. When the patchis applied to the tobacco rod, the ribs run longitudinally along thelength of the rod, and extend radially between the two flat layers. Theterm “corrugated material” is intended to include structurally similarpatch materials that provide a plurality of parallel longitudinal smokepaths.

Alternatively, embossed material may be used for the patch, having apattern of indentations embossed into its surface and arranged toprovide paths along the length of the patch when positioned in thesmoking article. The indentations may be substantially straight andarranged parallel to the length of the tobacco rod, providing astructure largely equivalent to a single-sided corrugated patch.Alternatively, the indentations may be curved, or straight but arrangedat an angle to the length of the tobacco rod. Such configurationsprovide smoke paths that are longer than the longitudinal extent of thepatch, which can be used to further modify the smoke delivery from thetobacco upstream of the patch.

A similar effect to embossed material can be achieved by using a groovedmaterial, by arranging the grooves to provide paths for smoke upstreamof the patch.

The patch may be coloured to assist recognition by defect detectionsystems commonly employed during smoking article manufacture to identifycompleted or partially completed smoking articles that have one or moremissing or defective components. Such detection systems may be opticalsystems that monitor the amount of light at one or more wavelengths thatis transmitted by or reflected from various components. Thus, if thepatch is a different colour from the tobacco and/from the paper wrapper,its presence or absence from the completed smoking article can bedetermined using an optical detection system.

In many examples, in order to provide a useful level of modification tothe smoke delivery, the patch will have a thickness that is much greaterthan the typical thickness of a standard paper wrapper (cigarettepaper). The thickness of the patch may be between 5 and 50 times thethickness of the paper wrapper, for example. This corresponds to a patchwith a thickness substantially in the range 0.2 mm to 2 mm. Duringfabrication of the smoking article, the patch may be positioned aroundthe tobacco rod before the paper wrapper is applied, or the patch may beadhered to the paper wrapper before the latter is wrapped around thetobacco rod (in a similar manner to the technique described in WO2005/082180 for providing a web of adsorbent material and flavourantunder the wrapper of a smoking article). In either case, to achieve asubstantially constant diameter along the length of the smoking article,the tobacco under the patch will be compressed. The tobacco in theupstream portion of the tobacco rod will therefore be less dense thanthe tobacco in the downstream portion of the tobacco rod. This willfurther affect both the relative resistance to smoke flow offered by thetobacco and the patch, and the static burn rate of the second portion ofthe smoking article.

To address these additional effects, it is proposed according to afurther embodiment that the width of the tobacco rod be reduced underthe patch, to give a reduced weight of tobacco per unit length under thepatch compared to upstream of the patch. This can be achieved byremoving some tobacco from the tobacco rod, for example by using one ormore trimmer (ecreteur) discs (such as are conventionally used to size,shape and tidy the tobacco bead in smoking article manufacture) to cutaway a portion of tobacco from the continuous bead of tobacco from whichthe rods are cut.

FIG. 10 shows a side view of a tobacco rod 12 which has been shaped inthis way. One end of the rod 12, destined to be the upstream end A ofthe smoking article has a diameter a, and the other end of the rod 12,destined to the downstream, mouth, end B of the smoking article has asmaller diameter b. The difference between these diameters issubstantially the same as the thickness of the material forming thepatch, so that when the patch is positioned around the smaller diameterpart of the tobacco rod, the tobacco rod and patch combination is of asubstantially uniform diameter. This gives a finished smoking articlewith a smooth outer surface and a constant tobacco density.

Thus far, the smoking articles described herein have comprised tobaccorods, wrapping papers and patches, thus providing filterless smokingarticles. In such a case, a colour or other distinguishing mark orfeature may be applied to the outside of the wrapper at the mouth end ofthe finished smoking article, to assist the consumer in correctlyidentifying the mouth end before smoking. Alternatively, the tobaccorods may be provided with filter units to provide filter-tipped smokingarticles in the conventional manner, wherein a filter unit is joined tothe mouth end of a wrapped tobacco rod by a tipping paper. The filterunit may have any configuration, including single component or multiplecomponent, and may or may not be provided with ventilation such as acircumferential row or zone of ventilation holes made by on-line lasermachining or provided by pre-perforations. Thus, the term “smokingarticle” as used herein is intended to include filterless smokingarticles comprising a tobacco rod with no filter unit, filter-tippedsmoking articles comprising a tobacco rod with an attached filter unit,and tobacco rods without filters but to which a filter unit may beattached by a later fabrication stage to form a filter-tipped smokingarticle.

FIG. 11 shows a longitudinal cross-sectional view of a filter-tippedsmoking article 10 comprising a tobacco rod 12, paper wrapper 14 andpatch 16 as illustrated in FIG. 1, plus a filter unit 44 joined to thetobacco rod 12 by a tipping paper 46 that encircles the filter unit 44and overlaps the end of the tobacco rod 12 over the paper wrapper 14 inthe known manner. The filter unit 44 is provided with ventilation in theform of a row of pre-perforated holes 48 formed in the tipping paper 46.

The term “tobacco” as used herein is intended to be understood asincluding smokable material in general, including tobacco material (suchas stem, lamina, tobacco dust, cut tobacco and expanded tobacco),reconstituted tobacco and substitute tobacco materials.

1. A smoking article comprising: a tobacco rod; a wrapper around thetobacco rod; and a patch of material positioned between the tobacco rodand the wrapper and extending longitudinally along the tobacco rod froman intermediate point along the tobacco rod towards a mouth end of thetobacco rod, the material having structure such that the patch providesa path for smoke from tobacco upstream of the patch towards the mouthend that has less resistance to smoke flow than a path through thetobacco under the patch, and wherein the patch comprises at least oneburn-enhancer to increase the static burn rate of the smoking articleover the length comprising the patch.
 2. The smoking article accordingto claim 1, wherein the patch extends longitudinally from theintermediate point to the mouth end of the tobacco rod.
 3. The smokingarticle according to claim 1, wherein the patch extends longitudinallyfrom the intermediate point to a second point between the intermediatepoint and the mouth end.
 4. The smoking article according to claim 3,wherein the second point is between 1% and 40% of the total length ofthe tobacco rod from the mouth end.
 5. The smoking article according toclaim 1, wherein the patch extends longitudinally over substantially 10%to 90% of the total length of the tobacco rod.
 6. The smoking articleaccording to claim 5, wherein the patch extends longitudinally oversubstantially 40% to 80% of the total length of the tobacco rod.
 7. Thesmoking article according to claim 1, wherein the patch extendssubstantially around the whole circumference of the tobacco rod.
 8. Thesmoking article according to claim 1, wherein the patch comprises one ormore portions of material disposed around the circumference of thetobacco rod.
 9. The smoking article according to claim 1, wherein thepatch comprises a foam material.
 10. The smoking article according toclaim 1, wherein the patch comprises a corrugated material havingcorrugations that extend substantially longitudinally along the tobaccorod.
 11. The smoking article according to claim 10, wherein thecorrugated material has a laminate structure comprising a corrugatedlayer and a non-corrugated layer.
 12. The smoking article according toclaim 11, wherein the non-corrugated layer is positioned between thetobacco rod and the corrugated layer.
 13. The smoking article accordingto claim 49, wherein the non-corrugated layer is positioned between thecorrugated layer and the paper wrapper.
 14. The smoking articleaccording to claim 10, wherein the corrugated material has a laminatestructure comprising a corrugated layer sandwiched between twononcorrugated layers.
 5. The smoking article according to claim 1,wherein the patch comprises an embossed material having indentationsthat extend substantially longitudinally along the tobacco rod.
 16. Thesmoking article according to claim 1, wherein the patch comprises agrooved material having grooves that extend substantially longitudinallyalong the tobacco rod.
 17. The smoking article according to claim 1,wherein the patch comprises a fibrous sheet material.
 18. The smokingarticle according to claim 1, wherein the patch has a color differentfrom the wrapper and the tobacco rod.
 19. The smoking article accordingto claim 1, wherein the tobacco rod has a reduced weight of tobacco perunit length under the patch compared to upstream of the patch.
 20. Thesmoking article according to claim 19, wherein the reduced weight iscreated by trimming tobacco from the outside of the tobacco rod.
 21. Thesmoking article according to claim 19, wherein the reduced weight iscreated by trimming tobacco from a tobacco bead from which the tobaccorod is to be cut.
 22. The smoking article according to claim 1, whereinthe smoking article further comprises a filter unit attached to themouth end of the tobacco rod.
 23. The smoking article according to claim22, wherein the filter unit is provided with one or more ventilationholes.
 24. A method of fabricating a smoking article comprising:providing a rod of tobacco; disposing a patch of material over the rodof tobacco such that the patch extends longitudinally along the rod froman intermediate point along the rod towards a mouth end of the rod, thematerial having a structure and the patch being oriented such that, inthe completed smoking article, the patch provides a path for smoke fromtobacco upstream of the patch towards the mouth end that has lessresistance to smoke flow than a path through the tobacco under thepatch, wherein the patch comprises at least one burn-enhancer toincrease the static burn rate of the smoking article over the lengthcomprising the patch; and wrapping a wrapper around the rod.
 25. Themethod according to claim 24, wherein disposing the patch of materialcomprises positioning the patch on the rod of tobacco before wrappingthe wrapper around the rod.
 26. The method according to claim 50,wherein disposing the patch of material comprises adhering the patch toan inner surface of the paper wrapper before wrapping the wrapper aroundthe rod.
 27. The method according to claim 24, wherein the patch extendslongitudinally from the intermediate point to the mouth end of the rodof tobacco.
 28. The method according to claim 24, wherein the patchextends longitudinally from the intermediate point to a second pointbetween the intermediate point and the mouth end.
 29. The methodaccording to claim 28, wherein the second point is between 1% and 40% ofthe total length of the rod of tobacco from the mouth end.
 30. Themethod according to claim 24, wherein the patch extends longitudinallyover substantially 10% to 90% of the total length of the rod.
 31. Themethod according to claim 30, wherein the patch extends longitudinallyover substantially 40% to 80% of the total length of the rod.
 32. Themethod according to claim 24, wherein the patch extends substantiallyaround the whole circumference of the rod of tobacco.
 33. The methodaccording to claim 24, wherein the patch comprises one or more portionsof material disposed around the circumference of the rod of tobacco. 34.The method according to claim 24, wherein the patch comprises a foammaterial.
 35. The method according to claim 50, wherein the patchcomprises a corrugated material having corrugations, the patch beingdisposed such that the corrugations extend substantially longitudinallyalong the rod of tobacco.
 36. The method according to claim 35, whereinthe corrugated material has a laminate structure comprising a corrugatedlayer and a non-corrugated layer.
 37. The method according to claim 36,wherein the patch is disposed such that the non-corrugated layer ispositioned between the tobacco rod and the corrugated layer.
 38. Themethod according to claim 36, wherein the patch is disposed such thatthe noncorrugated layer is positioned between the corrugated layer andthe paper wrapper.
 39. The method according to claim 35, wherein thecorrugated material has a laminate structure comprising a corrugatedlayer sandwiched between two noncorrugated layers.
 40. The methodaccording to claim 24, wherein the patch comprises an embossed material,the patch disposed such that indentations in the material extendsubstantially longitudinally along the rod of tobacco.
 41. The methodaccording to claim 24, wherein the patch comprises a grooved material,the patch disposed such that the grooves extend substantiallylongitudinally along the rod of tobacco.
 42. The method according toclaim 24, wherein the patch comprises a fibrous sheet material.
 43. Themethod according to claim 50, wherein the patch has a color differentfrom the paper wrapper and the rod of tobacco.
 44. The method accordingto claim 24, wherein the rod of tobacco has a reduced weight of tobaccoper unit length under the patch compared to upstream of the patch. 45.The method according to claim 24, further comprising: trimming tobaccofrom outside of the rod of tobacco over an area where the patch is to bedisposed, thereby creating a reduced weight; and disposing the patchover the rod of tobacco so that the patch covers the area from whichtobacco has been trimmed.
 46. The method according to claim 24, furthercomprising: trimming tobacco from outside of a bead of tobacco over anarea where the patch is to be disposed, thereby creating a reducedweight; cutting a rod of tobacco from the bead; and disposing the patchover the rod of tobacco so that the patch covers the area from whichtobacco has been trimmed.
 47. The method according to claim 24, furthercomprising attaching a filter unit to the smoking article.
 48. Themethod according to claim 47, wherein the filter unit is provided withone or more ventilation holes.
 49. The smoking article according toclaim 11, wherein the wrapper is a paper wrapper.
 50. The methodaccording to claim 24, wherein the wrapper is a paper wrapper.